New technology of power augmentation on horizontal axis wind turbines using Mie vanes

Wind turbine performance can be significantly improved by Mie vanes attached to the tips of rotor blades. These small tip attachments, developed at Mie University, feature a considerable power augmentation. At the ECWEC '90 Madrid conference windtunnel experiments were presented in which a maximum power coefficient CP = 0.45 at ¿ = 4 was established. This is an augmentation of 27% with respect to the base line (no Mie vanes). Since then more experimental and theoretical work has been performed. With a new model rotor equipped with tapered blades a base line peak CP equal to 0.41 is found at a tipspeed ratio ¿ = 5. With Mie vanes a maximum CP equal to 0.48 was reached at the same tipspeed ratio. From the theory developed it is concluded that the physical principles are understood. Still more experimental data need to be gathered in order to tune the theoretical model in such a way that more firm conclusions about the potentials of the concept can be drawn. © 1992